No matter what your style, no matter what your taste in plants there's one thing that every garden should have - and that's mulch.
Nature creates mulch by the leaves, twigs and plant debris that fall to the ground to make a varied and matted cover. This blanket is porous, in that it lets the rain seep through yet, when it's thick enough, it provides a major discouragement to weeds that may already be in the soil by depriving them of light.
It also provides an unstable and difficult base for new weed seeds to lodge in.
In summer it insulates like a thermal blanket keeping the top soil cool and therefore minimising evaporation of water and damage to shallow rooted plants like azaleas.
In winter it does the opposite keeping in the warmth of the day to keep the roots warmer.
So all year round your soil will be kept in a more moderate and balanced state, encouraging better root growth, more worms and beneficial organisms and as a result of all these it will be better structured and drained.
Most importantly it will reduce your need to water the garden, helping to maintain the environment and saving you time and money.
Nature's own mulch is everywhere and it has done a terrific job for millions of years.
So how do you go about re-creating it in your very ordered backyard.
Basically there is not a part of the garden that shouldn't be mulched - all garden beds and borders, shrubberies, under trees, under groundcovers, rockeries and banks even all your pots and tubs as well. Even if you don’t plan to have plants grow in some areas then still mulch it to keep the weeds at bay and for its fine decorative effect.
Purchase a good amount - if you just have a few pots on the patio then a bag or two of mulch will do but otherwise you'll need quite a lot to make it worthwhile. A fair few cubic meters will be necessary for most gardens and that'll take a truck to deliver it.
Types of Mulch:
• Pine bark is one of he most popular mulches - it comes in various chip sizes and will mat together quite well.
• Cypress wood chip and eucalyptus wood chip are other good looking mulches that makes a good mat and can be purchased in various shades from golden yellow to a deep red. This is achieved with harmless organic stains and are for cosmetic purposes only and will fade in time.
• Leaf litter is as its name suggests and is often the output of those large "Tree Gobblers" that local councils now use to chop up street tree prunings.
• Sugar Cane and Tea Tree - these arec pulverised from the plant of their name and make a dense mat on the surface. Both are soft and easy to re-arange around smaller plants like veggie seedlings. They both suppress weeds quite well and the Tea Tree Mulch takes much longer to compost down - its more expensive but you'll replace it less often. Sugarcane mulch is relatively cheap but should be replaced every year.
• Gravels - they don't decompose but they do everything else very well.
Spreading it About:
The one disadvantage of mulch is that it can rob the soil of nitrogen when it starts to decompose - so sprinkle some blood and bone or nitrogen rich fertilisers over the soil first.
Alternatively you can spread an underblanket of compost or easily compostable materials like sawdust, straw, grass cutings etc. first then cover it over with mulch. Wether you do this or not, always water the ground well first, and again after you've finished, it helps bind the mulch together and establish good water seepage through the new mulch mat.
Whatever you buy make sure that you calculate enough to provide a good cover depth.
In general spread your mulch around 10 - 12cms deep - its best to buy a bit too much than not enough as you can pile up the left overs in a corner of the garden to top up areas that may thin out due to wind loss etc.. (and you'll never bother to go and get a bag or two to top up later, will you?).
If you live in a windy area then make sure you buy a mulch that is rough edged and medium to large in size - like Forest Fines. These rough edges bind together and will make a good strong mat to withstand the wind.
Fertilising:
It’s a good idea to apply some fertiliser to mulched areas in springtime and perhaps also in autumn to counteract the slight nitrogen negative effect. (You can tell if the soil is nitrogen deficient as the leaves will go yellow).
Water solulable fertilisers are good like sulphate of ammonia or you can sprinkle a little Urea which is the purest form of nitrogen and can be bought in bags of small white granules.
The best way however is to pull back the mulch and rake in some blood and bone into the top soil then replace the mulch. This is a slow release form of nitrogen and is the most gentle of the lot and will be tolerated by most natives that normally hate phosphorous heavy fertilisers.
Whichever form of fertilising you choose, always ensure you water the area well first and again afterwards to help get the goodness down into the soil. If your soil has developed a water repellant quality (and many soils will, particularly sandy soils) then you should also apply a soil wetting agent which breaks down surface tension and allows the soil particles to thoroughly absorb and maintain the water.
Newspaper Underblanket:
If you are worried that your soil is already infested with weeds seeds you can lay a few sheets of newspaper down first and spread the mulch on top. This will form an inpeneterable barrier for new weed seeds germinating yet the paper will let the water seepthrough. Just make sure you cover it deep enough so the classifieds don't peep through in a week or two.
N.B. Just in case there's anyone out there who still thinks that black plastic underneath mulch is the best way to stop weeds - DON'T EVEN THINK ABOUT IT - it’s the worst thing you can do to any patch of soil as it deprives it of water and air - result death to everything, plants, worms, good bugs and organisms etc.
Steep Banks:
Mulch can also help to stabilise soils on steep banks. A good, deep layer of rough edged woodchip of a decent size (5-6 cms) makes a good start then cover the area with a fine garden netting and stake it down at regular intervals.
Topping Up:
Mulching is not, however, a one off exercise. An added benefit of a good mulch is that it will decompose and rot down into the top layers of the soil - the worms will then pull it down to help keep the soil well drained.
So top up your garden beds at least once a year, keeping the cover around 10 - 12 cms deep.
Its easy to make the effort once and forget it but you'll eventually see weeds making their way through.
All coloured mulches will fade. That lovely redwood chip that looks fabulous when you spread it all around for the first time will eventally go grey. So for those who have colour co-ordinated "Designer" gardens beds - be prepared to re-dress.
Gravel Mulch:
Some think that mulches can only be organic - but gravels make an excellent mulch as well, though they do not decompose and feed the soil.
They are very decorative and deter the weeds probably better than wood chips but they also have an added bonus. For those who worry about security, the gravel flower beds will deter the most ardent burglar as it makes a noise to walk on. Gravel under any window or as a path leading up to doorways will make most crims think twice about walking across it - a great burgler alarm.
And for those who recognise the beauty and serenity of Japanese garden designs, gravels raked into patterns can add a distinct extra element of character to your garden.
It is important to lay a porous membrane on the soil surface first - you can buy a roll of gravel underlay from the same supplier of the gravel. This stops the gravel and soil mixing together and allows you to remove the gravel mulch later with ease.
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